52. Constant Directivity Circular-Arc Arrays of Dipole Elements

AES Convention: 143 Paper Number:9837
Publication Date: 2017-10-06

We develop the theory for a broadband constant-beamwidth transducer (CBT) formed by a conformal circular-arc line array of dipole elements. Just as for CBT arrays of point sources, with suitable amplitude shading of the source distribution the far-field radiation pattern is constant above a cutoff frequency. This cutoff frequency is determined by the prescribed beam width and arc radius. We illustrate the theory with examples, including numerical simulations of magnitude responses, full-sphere radiation patterns, and directivity index. Unlike a circular-arc array of monopole elements, a dipole CBT maintains directivity control at low frequency. We give an example of one such array that achieves just 1 dB variation in directivity index over all frequencies.